Selling inferior products

Purchased a Cadac gass Heater from Makro Montague Gardens in May 2017. This heater has a two year warranty. In June 2018 this heater started giving me problems. Took it back to Makro for repairs. Collected it three weeks later now in July. Heater worked, broke again the same issue in August 9. This same heater has given me the same problem within less than two months. Took it back to returns at Makro and demanded a refund or a new heater. Three weeks later, yesterday they called me to collect this heater once again. I will not collect this heater. I demand a refund or a new heater. This is dayl